1. Field of the Invention
The invention pertains to patient warmer heater blower control systems wherein hot air is distributed over the patient's body through an air pervious blanket, the circuitry controlling the temperature of the air utilizes several safety features to prevent overheating and a self-test cycle to simulate overheating for testing operational characteristics.
2. Description of the Related Art
Hypothermic therapy systems are used to return the patient to a normal body temperature after surgery, shock, immersion in water, or the like. In such instances, it is necessary to bathe the patient's body in warm air to return the body temperature to normal.
Known hypothermic therapy devices include inflatable envelopes or blankets placed above, below, or around the patient's body having small orifices directed toward the patient whereby the warm air is directly applied to the patient. As the temperature of the air being imposed upon the patient must be closely regulated and predetermined, a control system for the apparatus supplying the heated air must include accurate temperature regulation features to prevent overheating of the patient which could inflict serious injury or even be fatal.
While it is known to use thermostatic controls with air heaters utilizing electric resistant heating elements, such thermostatic controls simply sense the temperature of the gas, air or adjacent apparatus, and in the event of malfunction the circuitry is not self-analyzing and overheating may occur.
Known hypothermic therapy systems using electric resistant heaters to heat air do not employ temperature indicators to assess the actual temperature of the air being supplied and do not employ dual safety circuits to de-energize the heater element and do not employ self-testing circuits for determining the operability of the circuit safety features, and the possibility for malfunctioning exists in presently available systems.